The present invention relates to a method for producing collar or flange shaped reinforcements on cylindrical composite fiber bodies, and particularly on wound composite fiber pipes or tubes, in which several layers of resin impregnated fiber layers are wound on top of one another along the regions of the composite body to be reinforced, after which the resin is hardened.
German Patent No. 3,029,890, which corresponds to U.S. Pat. No. 4,359,356, discloses a method of producing composite fiber pipes which have collar or flange shaped reinforcements at the ends of the pipes. In this case, several layers of circumferential and crisscross windings of plastic impregnated fibers, e.g. carbon fibers, are initially wound on top of one another on a winding mandrel. Then, additional circumferential windings are applied along the regions of the composite pipe to be reinforced. Thereafter the composite pipe is severed at the reinforced regions so that several pipe sections are obtained which have flange-like reinforced ends. However, the reinforcements obtained with this method have a thickness that is little more than the wall thickness of the composite pipe since the fiber windings at the sides of the reinforcements have a relatively flat slope angle, also referred to as a natural angle, i.e. the steepest angle which can be produced during winding as a consequence of the physical properties of the fiber being wound and the geometry of the structure formed by the winding process. However, these sides of the reinforcements take up additional space as compared with a reinforcement having orthogonal flange walls. This is a primary reason why it is not possible using this type of known technology, i.e. by winding only perpendicularly to the longitudinal axis of the pipe, to produce flange faces of a conventional shape having orthogonal flange walls as are used, for example, for flanges of metal pipes which have side walls that extend perpendicularly to the longitudinal axis of the pipe.